Construction for mounting a door of a pit mounted pressure vessel

ABSTRACT

A hinge arrangement is provided for supporting the door of a pit mounted pressure vessel for vertically reciprocating and horizontally swinging opening-closing movements, whereby to minimize the &#39;&#39;&#39;&#39;bridging&#39;&#39;&#39;&#39; distance between the vessel and the front of the pit.

United States Patent Piegza 1 June 10, 1975 [54] CONSTRUCTION FOR MOUNTING A DOOR 2,927,737 341960 Maher 49/I;38 X P VE 3,125,232 3 I964 Brinkman et al. 49 68 x OF A IT MOUNTE? PRESSURE SSEL 3,346,992 l0/l967 Lodge 49/255 Inventor: ry J- Plegza, arence, NY. 3,820,282 6/l974 Komylak 49/255 [73] Assignee: WSF Industries Inc., Tonawanda,

Primary Examinerl(enneth Downey [22] Filed: May 30, 1974 Attorney, Agent, or FirmBean & Bean [21] Appl. No.: 474,311

[52] US. Cl. 49/255; 49/280; 49/334; [57] ABSTRACT 49/340; 214/18 R [51] Int. Cl EOSi 7/02 A hinge arrangement is provided for supporting the Field seal'dl 3 door of a pit mounted pressure vessel for vertically re- 49/338-340, 344, 280; l09/70, 69, 87; ciprocating and horizontally swinging opening-closing 214/ 17-182 movements, whereby to minimize the "bridging" distance between the vessel and the front of the pit.

[56] References Cited UNITED STATES PATENTS 2,865,629 l2/l958 Henkel 49/280 X 11 Claims, 5 Drawing Figures 23 3 84 86 73 m u 78 52 l CONSTRUCTION FOR MOUNTING A DOOR OF A PIT MOUNTED PRESSURE VESSEL BACKGROUND OF THE INVENTION It is conventional to mount a horizontally disposed pressure vessel within a pit of a depth sufficient to permit a dolly or other material carrier to be rolled horizontally into the vessel over a removable bridge when the vessel door is in open position.

Most installations employ vessels having conventional horizontally swinging doors and thus require the front wall of the pit to be spaced from the front of the vessel through a distance approximating the diameter of the door in order to permit the latter to be swung into a fully open position. The disadvantages of this type of installation is that the bridge, which must have a length sufficient to bridge between the vessel and the floor in front of the pit. is necessarily heavy and cumbersome to position and remove when the vessel door is opened and closed.

The bridging" distance between the vessel and the front of the pit and thus the length of the bridge may be minimized by employing a vessel door supported for vertical swinging or reciprocating movements. However. this type of construction is expensive, ofttimes creates a serious head room problem and may present a serious safety problem.

SUMMARY OF THE INVENTION The present invention relates to a hinge arrangement for supporting the door of a pit mounted pressure ves sel for both vertically reciprocating and horizontally swinging opening-closing movements in order to minimize the bridging distance between the vessel and the front wall of the pit without creating a safety hazard when the door is in open position.

More specifically, the present hinge construction features a door mounting bearing shaft which is rotatably and slideably supported by a pair of vertically spaced vessel wall mounted bearings; a non-rotatable lift control cylinder which is connected to the lower end of the bearing shaft by a rotatable thrust bearing for effecting vertical reciprocating movements of the bearing shaft and door; and a swing control cylinder, which is end connected to the door and vessel wall for universal movement and is operable to effect horizontal swinging movements of the door about the axis of the bearing shaft. The door may be opened by first operating the swing control cylinder to swing the door sufficiently to clear the door-vessel locking arrangement. by then operating the lift control cylinder to lift the door sufficiently to clear the floor in front of the pit. and finally by again operating the swing control cylinder to swing the door into its fully open position. The savings in bridging distance between the vessel and the floor in front of the pit achieved by employing the present hinge construction permits the bridge to be formed as a permanent part of the pressure vessel and be of sufficiently light weight to permit it to be manually pivoted between stored and "bridging" positions when the vessel door is in open position. As by way of example, pressure vessels employing the present invention and having door diameters of feet. 9 feet and I5 feet would require bridges having lengths of approximately 1 /2 feet. 2 feet and 3 feet. respectively.

DRAWINGS The nature and mode of operation of the present invention will now be more fully described in the following detailed description taken with the accompanying drawings wherein:

FIG. 1 is a perspective view ofa pit mounted pressure vessel employing the present hinge construction with the vessel door shown in open position.

FIG. 2 is a front elevational view showing the door in closed position;

FIG. 3 is a side elevational view showing the door in closed position;

FIG. 4 is a top plan view showing the door in closed position, as well as various stages of opening; and

FIG. 5 is a diagrammatic view of the control system employed in the present invention.

DETAILED DESCRIPTION In FIGS. l4 of the drawings. a pressure vessel modifled in accordance with the present invention is designated as and shown as being partially received within a pit 12 having bottom, side and front walls 14. I5 and 16, respectively. Vessel 10 generally includes a horizontally disposed, generally cylindrical shell I8. which may be suitably supported on pit bottom wall I4. as by a stand a door 22 for normally closing shell access opening 24; a door locking mechanism 26; a door mounting and operating mechanism 28; and a bridge device 30 adapted to removably bridge the space or distance between a shell interior mounted m aterial support. such as tracks 32. and the floor surface 34 in front of pit front wall 16. As in conventional vessel installations of this type. the depth of pit 12 is sufficient to permit a dolly or other material carrier. not shown. to be rolled horizontally from floor 34 across bridge device 30 and onto tracks 32.

Door locking mechanism 26 is preferably of the type disclosed for example in US. Pat. No. 3.488.883. wherein a locking ring of essentially U-shaped cross section is mounted for rotation about an axis extending coaxially of shell 18 and in straddling association with an annularly extending flange 42, which bounds access opening 24 and defines a radially extending annular surface 44 against which a corresponding radially extending annular surface 46 of door 22 is adapted to seat in a pressure fluid sealed relationship when the door is locked in closed position. A forwardly facing leg portion 400 of locking ring 40 is provided with a plurality of circumferentially spaced through slot openings 48. which define intermediate portions 50 having tapered wedge elements. not shown. fixed to their relatively inwardly disposed surfaces. In a like fashion door 22 is provided with a plurality of circumferentially spaced through slot openings 52, which define intermediate portions 54 on which are mounted wedge elements. not shown. It will be understood that when door 22 is moved into a closed position in the manner to be described. intermediate portions 54 are adapted to pass through locking ring slot openings 48 to place surfaces 44 and 46 in juxtaposition with the surfaces of the wedge elements being disposed in a facing. circumferentially spaced relationship. Thereafter. when the locking ring is rotated in the direction indicated by arrow into its locked position illustrated in FIG. 2. as by operation of one or more fluid cylinders 62, the surfaces of the wedge elements cooperate to force the door into tight fluid pressure sealing relationship with flange 42. A suitable safety interlock or latch device 64, such as that disclosed in my copending application Ser. No. 3l2,l86, filed Dec. 4, 1972, may be used to releasably retain locking ring 40 in its locked position.

The pressure vessel of the present invention departs from conventional pit mounted pressure vessels of which I am aware in the novel construction of door mounting and operating mechanism 28, which serves to substantially reduce the spacing between the front end of shell 18 and pit front wall 16 necessary to accommodate for opening movements of door 22. More specifi cally, mechanism 28 comprises a shell side wall mounted or first hinge part 70, which serves to mount vertically aligned upper and lower sleeve bearing devices 72 and 74; a vertically extending bearing shaft 76, which is rotatably and slideably supported by sleeve bearings 72 and 74; a door mounting or second hinge part 78, which has one end thereof suitably keyed for movement with bearing shaft 76 and has an opposite end fixed to door 22', a nonrotatable pit mounted lift control cylinder 80, which is movably connected or coupled to the lower end of bearing shaft 76 by a rotatable thrust bearing 82; and a swing control cylinder 84, which is opposite end connected to the wall of shell 18 and second hinge part 78 as by suitable universal couplings 86 and 88, respectively. Alternatively, lift control cylinder 80 may be directly connected to the second hinge part, and coupling 88 may be directly connected to the bearing shaft.

Preferably, second hinge 78 would be coupled to door 22 via a third hinge part and adjustable bearing mechanism 90 of the type described in above mentioned U.S. Pat. No. 3,488,883. By this construction, door 22 is carried by shaft 76 for horizontal swinging movements under the control of swing control cylinder 84 and for vertical reciprocating movements under the control of lift control cylinder 80.

To facilitate understanding of the mode of operation of mechanism 28, specific reference is made to FIGS. 3 and 4, wherein D-l, D-2, D-3 and D4 designate the positions assumed by universal coupling 88 when door 22 is in its fully closed, first intermediate, second intermediate and fully open positions, respectively.

Cylinders 80 and 84 are part of a control system including electrical and fluid circuits shown in part in FIG. 5. This system includes lift control cylinder limit switches LS-3, LS-S and LS-9, which are arranged within control box 92 for cooperation with an operator 94 fixed for vertical movements with piston rod 96 of control cylinder 80; microswitches LS-2, LS-4, LS-6 and LS-7, which are arranged within control box 100 and cooperate with operator 102 fixed for movement with piston rod 104 of swing control cylinder 84; shell wall mounted microswitches LS-l and LS-8, which are responsive to movements of locking ring 40 into its locked and unlocked conditions, respectively; and microswitch LS-ll), which is located on safety interlock 64 and responsive to the condition thereof. These microswitches serve to control pairs of solenoids SV-lA and SV-lB, SV-2A and SV-ZB, and SV-3A and SV-3B, which control the condition of valves 110, 112 and 114, which in turn serve to connect locking ring control circuit 120, swing cylinder control circuit 122 and lift cylinder control circuit 124, respectively, with a source of fluid under pressure, such as pump 126.

Again referring to Hg. 5, it will be seen that swing cylinder control circuit 122 includes a first counterbalance valve 130, which is arranged in conduit 122a connected into the front end of the cylinder portion 131 of cylinder 84 to apply fluid for the purpose of driving piston 104 towards a contracted or door open condition and a second counterbalance valve 132, which is arranged in conduit l22b connected into the rear end of cylinder portion 131 to apply fluid for the purpose of driving piston 104 towards door closed condition; valves and 132 including check valves 130a and 1320, bypass valves 130b and 132b, and bypass valve controllers 130s and 132C, which are arranged in flow communication with and responsive only to the presence of pump pressure in conduits l22b and 122a, respectively. Also, it will be seen that lift cylinder control circuit 124 includes a third counterbalance valve 134, which is arranged in conduit 1240 connected into the lower end of the cylinder portion 135 of cylinder 80 to apply fluid for the purpose of driving piston 96 towards an extended or door elevated position; valve 134 including a check valve 1340, a bypass valve 134b, and a bypass valve controller 134C, which is arranged in flow communication with conduit 1241) connected into the upper end of cylinder portion 135. It will be understood that the check valves of valves 130, 132 and 134 serve to prevent exhausting of fluid from cylinders 80 and 84 through their associated conduits until positive operating or pump pressure is applied to their associated bypass valve controllers. By this arrangement piston 104 of swing cylinder 84 is releasably locked against both door opening and closing movements whenever control valve 112 is in its closed or inoperative condition illustrated in FIG. 5. ln a like manner, piston 96 of lift cylinder 80 is releasably locked against door lowering movement until control valve 114 is op erated to connect conduit 12411 to pump 126. This is a particularly desirable feature of the present invention in that it affords precise control of intended vertically reciprocating and horizontal swinging opening and closing movements of door 22 in the manner to be described, as well as serving to prevent uncontrolled and potentially dangerous movements of the door in the event of a failure in the control system.

To facilitate understanding of the mode of operation of the present invention, it will be assumed that door 22 is in its fully closed condition, i.e., coupling 88 is in its D'l position, locking ring 40 is in its locked condition and safety interlock 64 is operable to prevent unlocking rotations of the locking ring. Thus, lift control cylinder 80 is in its fully retracted position, which is sensed by switch LS-S and swing control cylinder 84 is in its fully extended position, which is sensed by switch LS-6. Preferably, safety interlock switch LS-lO is arranged in series circuit with a switch, not shown responsive to the pressure within shell 18, such as to require that vessel pressure be essentially zero and the safety interlock to be in a locking ring releasing condition before the sole noid operators of any of valves H0, H2 and 114 can be energized.

Now assuming that the pressure within the vessel has been reduced to zero and safety interlock 64 has been manually opened, unlocking movements of locking ring 40 and subsequent opening movements of door 22 may be automatically controlled, if desired, by simply depressing an open" push button type switch, not shown, of an electrical control circuit, also not shown,

in which the previously described solenoids and microswitches are suitably arranged. The operation of this electrical control circuit is such that when the open push button switch is depressed, solenoid SV-lA is operated to open valve 110 to effect extension of cylinders 62 and resultant rotation of locking ring 40 into its unlocked condition, which is sensed by switch LS-l. The closing of switch LS-l serves to deenergize solenoid SV-1A and to energize solenoid SV-2B, which serves to operate valve 112, whereby to place cylinder 84 in flow communication with pump 126 via valve 130 to effect contraction of cylinder 84 until operator 102 engages switches LS-2 and LS-4 at which point solenoid SV-ZB is deenergized. During this initial contraction of cylinder 84, coupling 88 is moved from its D-l position into its D-2 position and door 22 is swung horizontally about the axis of shaft 76 from its fully closed position into its first intermediate position, shown in phantom line as 22a in FIG. 4. The extent of horizontal swinging movement of door 22 is chiefly determined by the requirement that it fully clear or be removed from within the confines of locking ring 40, whereas the required spacing between the front of shell 18 and pit front wall 16 is determined by both the extent of this initial horizontal swinging momvement of the door and its diameter.

Further, upon operation of switches LS-2 and LS4, solenoid SV-3A is energized to operate valve 114 and place cylinder 80 in flow communication with pump 126 via valve 134, whereby to extend piston 96 and elevate bearing shaft '76 until operator 94 engages switches LS-3 and LS-9 at which point solenoid SV-3A is deenergized. During extension of cylinder 80, coupling 88 is moved from its D-2 position into its D-3 position and door 22 is moved vertically from its first intermediate position into its second intermediate position. The extent of vertical movement of door 22 is determined by the requirement that it be moved vertically from within the confines of the pit, so that it will fully clear floor surface 34 during its subsequent opening movement to be described. During extension of cylinder 80, piston rod 104 is locked in its intermediate or partially contracted position described above by operation of valves 130 and 132, such that coupling 88 moves vertically along an arc about the center of coupling 86, as indicated in FIG. 3. Although door 22 is subject to a back and forth horizontal swinging movement during this vertical movement of coupling 88, the extent thereof is so slight in view of the geometry of mechanism 28, as to produce a negligible increase in the required distance between shell 18 and pit front wall 16.

Further. upon operation of switches LS-3 and LS-9, solenoid SV-2B is again energized to effect continued contraction of cylinder 84 until operator 102 engages switch LS'7 at which point solenoid SV-ZB is deenergized. During this final contraction of cylinder 84, coupling 88 is moved horizontally from its D-3 position into its D-4 position and door 22 is again swung horizontally about the axis of shaft 76 from its second intermediate position into its fully open position designated as 22b in FIG. 4. The extent of horizontal swinging movement of door 22 is this time determined by the requirement that it be opened sufficiently to afford desired access to the interior of shell 18. Also, during and upon completion of this final contraction of cylinder 84, piston rod 96 of cylinder 80 is locked in its extended position by operation of valve 134, and when contraction of cylinder 84 is completed its piston rod is locked in its fully contracted position by operation of valves and 132.

When desired, door 22 may be automatically re turned to its fully closed position and locking ring 40 then returned to its locked position by depressing a close push button type switch, not shown, provided in the electrical control circuit. During the door closing and locking operation, the above described movements of door 22 and coupling 88 are merely reversed, but in this instance solenoids SV-lB, SV-2A and SV-3B are energized to control operation of valves 110, 112 and 114.

As indicated above the required spacing or distance between the front end of shell 18 and pit front wall 16 is chiefly determined by the extent of horizontal swinging movement of the door required to clear locking ring 40, i.e., remove the door from within the confines of the locking ring. However, this spacing is also to a degree proportional to the diameter of door 22. As for in stance, with the present construction, the length of bridge 30 required to span between tracks 32 and floor 34 will be approximately 1% feet, 2 feet and 3 feet for doors having diameters of 5V2 feet, 9 feet and 15 feet, respectively. This is, however, a substantial reduction in the length of bridge 30, as compared to conventional pressure vessel installations, and thus permits the bridge to be of a relatively light weight and inexpensive construction. Also, this short bridge length, as compared to door diameter, permits the bridge to be hingedly connected to the forward ends of tracks 32, as by hinge pins shown only in FIG. 1, whereby to permit the bridge to be folded upwardly for storage within the front of the pressure vessel when it is in use and then be manually lowered into the operative position shown in PK]. 1 after door 22 has been opened and it is desired to insert or remove material from the vessel.

I claim:

1. A door mounting mechanism for use with a horizontally disposed pressure vessel of the type having a shell defining access opening closeable by said door and a rotatable locking ring mechanism for releasably locking said door in access opening closed position. said shell being mounted within a pit of a depth sufficient to permit a material carrier to be moved essentially horizontally into and out of said shell when said door is in an open position over a bridge removably positioned to bridge between said shell and a floor surface in front of said pit, said mounting mechanism serving to mount said door for both vertical reciprocating and horizontal swinging opening-closing movements between open and closed positions, whereby the bridging" distance between said shell and said floor surface is less than that required to accommodate solely for horizontally directed swinging movements of said door between said positions, and said mounting mechanism comprising:

a vertically extending bearing shaft;

a first hinge part for mounting said bearing shaft for both horizontally directed rotary and vertically directed reciprocating movements;

a second hinge part having one end thereof affixed to said bearing shaft for movement therewith and an opposite end thereof connected to said door;

a lift control cylinder for imparting vertical reciprocating movements to said bearing shaft, whereby to effect vertical reciprocating movements of said door;

a swing control cylinder for imparting rotary movements to said bearing shaft; whereby to effect horizontal swinging movements of said door; and

circuit means for sequentially controlling operation of said lift and swing control cylinders, whereby in succession to swing said door horizontally from closed position sufficiently to clear said locking ring mechanism, to lift said door vertically sufficiently to clear said floor surface and to swing said door horizontally into said open position.

2. A mechanism according to claim 1, wherein said circuit means includes means for releasably locking said lift control cylinder in all door lifting positions thereof.

3. A mechanism according to claim 2, wherein said circuit means includes means for releasably locking said swing control cylinder in all conditions thereof.

4. A mechanism according to claim 1, wherein said lift control cylinder includes a vertically extending piston rod having its upper end supportingly coupled to a lower end of said bearing shaft by a rotatable thrust bearing; and said circuit means includes conduits connected into lower and upper ends of said lift control cylinder. valve means for selectively connecting said conduits to a source of fluid under pressure whereby to extend and retract said piston rod to lift and lower said bearing shaft, respectively, and means for releasably locking said piston rod in all extended positions thereof until operation ofsaid valve means to place said source of fluid under pressure in communication with said upper end of said cylinder, said locking means including a check valve arranged in the conduit connected in said lower end of said cylinder for permitting passage of fluid therethrough only in a direction towards said lower end of said cylinder, a bypass valve connected into said conduit across said check valve and a control for opening said bypass valve only in response to the operation of said valve means placing said upper end of said cylinder in communication with said source through the other of said conduits.

5. A mechanism according to claim 1, wherein said circuit means includes conduits connected into oppo site ends of said swing control cylinder, valve means for selectively connecting said conduits to a source of fluid under pressure whereby to retract and extend said swing control cylinder to effect horizontal swinging movement of said door. and additional valve means in each of said conduits for permitting flow of fluid from an associated end of said lift control cylinder only upon operation of said valve means to connect an opposite end of said cylinder to said source of fluid under pressure.

6. A pressure vessel comprising in combination:

a pressure vessel shell having a horizontally open access opening and mounting therewithin material support means accessible through said access opening. said shell being mounted within a pit for positioning said material support means in substantially horizontal alignment with a floor surface in front of said pit.

a door for removably closing said access opening;

locking means carried by said shell for releasably locking said door in access opening closed position,

said door when in said closed position being partially within the confines of both said pit and said locking means;

hinge means for supporting said door for both horizontally directed swinging and vertically directed reciprocating movements between said closed position and an access opening open position, wherein said door is removed from within the confines of both said pit and said locking means and disposed above said floor surface;

control means for effecting movement of said door between said closed and open positions successively through a first intermediate position effected by a horizontally swinging displacement of said door from said closed position to remove said door from within the confines of said locking means and a second intermediate position effected by a vertical displacement of said door from said first intermediate position to remove said door vertically from within the confines of said pit, said door being swung horizontally from said second intermediate position into said fully open position; and

a bridge for removably bridging the distance between said floor surface and said material support means when said door is in said open position.

7. A pressure vessel according to claim 6, wherein said bridge is pivotally supported by said material support means and dimensioned to permit upwardly directed swinging movement thereof to assume a bridge stored position within the confines of said shell.

8. A pressure vessel according to claim 6, wherein said hinge means includes a vertically extending bearing shaft, a first hinge part for mounting said bearing shaft for both horizontally directed rotary and vertically directed reciprocating movements, a second hinge part having one end thereof fixed to said bearing shaft for movement therewith and an opposite end thereof connected to said door; and said control means includes independent means for effecting rotary and reciprocating movements of said bearing shaft and corresponding horizontal swinging and vertical reciprocating movements of said door.

9. A pressure vessel according to claim 6, wherein said hinge means includes a vertically extending bearing shaft, a first hinge part fixed to said shell and carrying vertically aligned upper and lower bearing devices for supporting said bearing shaft for both horizontally directed rotary and vertically directed reciprocating movements. a second hinge part having one end thereof fixed to said bearing shaft for movement therewith and an opposite end thereof connected to said door; and said control means includes a lift control cylinder for imparting vertical reciprocating movements to said bearing shaft, said lift control cylinder having a cylinder portion fixed within said pit and a vertically displaceable piston rod arranged in vertical alignment with said bearing shaft. said piston rod having an upper end thereof connected to a lower end of said bearing shaft by a rotatable thrust bearing, a swing control cylinder for imparting rotary movements to said bearing shaft, said swing control cylinder having cylinder and piston rod portions thereof connected one to each of said shell and said second hinge part for relative universal movements. and fluid circuit means for sequentially controlling operation of said lift and swing control cylinders.

10. A pressure vessel according to claim 9, wherein said circuit means includes conduits connected into upper and lower ends of said lift control cylinder portion, valve means for selectively connecting said can duits to a source of fluid under pressure whereby to extend and retract its associated piston rod to lift and lower said bearing shaft, respectively, and means for releasably locking said associated piston rod in all extended positions thereof until operation of said valve means to place said source of fluid under pressure in communication with said upper end of said cylinder portion, said locking means including a check valve arranged within the conduit connected into said lower end of said cylinder portion for permitting passage of fluid therethrough only in a direction towards said lower end of said cylinder portion. a bypass valve connected into said conduit across said check valve and a control for opening said bypass valve only in response to the operation of said valve means placing said upper end of said cylinder portion in flow communication with said source of fluid under pressure through the other of said conduits.

H. A pressure vessel according to claim 10, wherein said circuit means additionally includes conduits connected into opposite ends of said swing control cylinder portion, valve means for selectively connecting the last said conduits to said source of fluid under pressure whereby to retract and extend said swing control cylinder piston rod to effect horizontal swinging movements of said door, and additional valve means in each of the last said conduits for permitting flow of fluid from an associated end of said lift control cylinder portion only open operation of the last said valve means to connect an opposite end of said swing control cylinder portion to said source of fluid under pressure. 

1. A door mounting mechanism for use with a horizontally disposed pressure vessel of the type having a shell defining access opening closeable by said door and a rotatable locking ring mechanism for releasably locking said door in access opening closed position, said shell being mounted within a pit of a depth sufficient to permit a material carrier to be moved essentially horizontally into and out of said shell when said door is in an open position over a bridge removably positioned to bridge between said shell and a floor surface in front of said pit, said mounting mechanism serving to mount said door for both vertical reciprocating and horizontal swinging opening-closing movements between open and closed positions, whereby the ''''bridging'''' distance between said shell and said floor surface is less than that required to accommodate solely for horizontally directed swinging movements of said door between said positions, and said mounting mechanism comprising: a vertically extending bearing shaft; a first hinge part for mounting said bearing shaft for both horizontally directed rotary and vertically directed reciprocating movements; a second hinge part having one end thereof affixed to said bearing shaft for movement therewith and an opposite end thereof connected to said door; a lift control cylinder for imparting vertical reciprocating movements to said bearing shaft, whereby to effect vertical reciprocating movements of said door; a swing control cylinder for imparting rotary movements to said bearing shaft; whereby to effect horizontal swinging movements of said door; and circuit means for sequentially controlling operation of said lift and swing control cylinders, whereby in succession to swing said door horizontally from closed position sufficiently to clear said locking ring mechanism, to lift said door vertically sufficiently to clear said floor surface and to swing said door horizontally into said open position.
 2. A mechanism according to claim 1, wherein said circuit means includes means for releasably locking said lift control cylinder in all door lifting positions thereof.
 3. A mechanism according to claim 2, wherein said circuit means includes means for releasably locking said swing control cylinder in all conditions thereof.
 4. A mechanism according to claim 1, wherein said lift control cylinder includes a vertically extending piston rod having its upper end supportingly coupled to a lower end of said bearing shaft by a rotatable thrust bearing; and said circuit means includes conduits connected into lower and upper ends of said lift control cylinder, valve means for selectively connecting said conduits to a source of fluid under pressure whereby to extend and retract said piston rod to lift and lower said bearing shaft, respectively, and means for releasably locking said piston rod in all extended positions thereof until operation of said valve means to place said source of fluid under pressure in communication with said upper end of said cylinder, said locking means including a check valve arranged in the conduit connected in said lower end of said cylinder for permitting passage of fluid therethrough only in a direction towards said lower end of said cylinder, a bypass valve connected into said conduit across said check valve and a control for opening said bypass valve only in response to the operation of said valve means placing said upper end of said cylinder in communication with said source through the other of said conduits.
 5. A mechanism according to claim 1, wherein said circuit means includes conduits connected into opposite ends of said swing control cylinder, valve means for selectively connecting said conduits to a source of fluid under pressure whereby to Retract and extend said swing control cylinder to effect horizontal swinging movement of said door, and additional valve means in each of said conduits for permitting flow of fluid from an associated end of said lift control cylinder only upon operation of said valve means to connect an opposite end of said cylinder to said source of fluid under pressure.
 6. A pressure vessel comprising in combination: a pressure vessel shell having a horizontally open access opening and mounting therewithin material support means accessible through said access opening, said shell being mounted within a pit for positioning said material support means in substantially horizontal alignment with a floor surface in front of said pit; a door for removably closing said access opening; locking means carried by said shell for releasably locking said door in access opening closed position, said door when in said closed position being partially within the confines of both said pit and said locking means; hinge means for supporting said door for both horizontally directed swinging and vertically directed reciprocating movements between said closed position and an access opening open position, wherein said door is removed from within the confines of both said pit and said locking means and disposed above said floor surface; control means for effecting movement of said door between said closed and open positions successively through a first intermediate position effected by a horizontally swinging displacement of said door from said closed position to remove said door from within the confines of said locking means and a second intermediate position effected by a vertical displacement of said door from said first intermediate position to remove said door vertically from within the confines of said pit, said door being swung horizontally from said second intermediate position into said fully open position; and a bridge for removably bridging the distance between said floor surface and said material support means when said door is in said open position.
 7. A pressure vessel according to claim 6, wherein said bridge is pivotally supported by said material support means and dimensioned to permit upwardly directed swinging movement thereof to assume a bridge stored position within the confines of said shell.
 8. A pressure vessel according to claim 6, wherein said hinge means includes a vertically extending bearing shaft, a first hinge part for mounting said bearing shaft for both horizontally directed rotary and vertically directed reciprocating movements, a second hinge part having one end thereof fixed to said bearing shaft for movement therewith and an opposite end thereof connected to said door; and said control means includes independent means for effecting rotary and reciprocating movements of said bearing shaft and corresponding horizontal swinging and vertical reciprocating movements of said door.
 9. A pressure vessel according to claim 6, wherein said hinge means includes a vertically extending bearing shaft, a first hinge part fixed to said shell and carrying vertically aligned upper and lower bearing devices for supporting said bearing shaft for both horizontally directed rotary and vertically directed reciprocating movements, a second hinge part having one end thereof fixed to said bearing shaft for movement therewith and an opposite end thereof connected to said door; and said control means includes a lift control cylinder for imparting vertical reciprocating movements to said bearing shaft, said lift control cylinder having a cylinder portion fixed within said pit and a vertically displaceable piston rod arranged in vertical alignment with said bearing shaft, said piston rod having an upper end thereof connected to a lower end of said bearing shaft by a rotatable thrust bearing, a swing control cylinder for imparting rotary movements to said bearing shaft, said swing control cylinder having cylinder and piston rod portions thereof connected one to each of said shell and said second hinge part for relative universal movements, and fluid circuit means for sequentially controlling operation of said lift and swing control cylinders.
 10. A pressure vessel according to claim 9, wherein said circuit means includes conduits connected into upper and lower ends of said lift control cylinder portion, valve means for selectively connecting said conduits to a source of fluid under pressure whereby to extend and retract its associated piston rod to lift and lower said bearing shaft, respectively, and means for releasably locking said associated piston rod in all extended positions thereof until operation of said valve means to place said source of fluid under pressure in communication with said upper end of said cylinder portion, said locking means including a check valve arranged within the conduit connected into said lower end of said cylinder portion for permitting passage of fluid therethrough only in a direction towards said lower end of said cylinder portion, a bypass valve connected into said conduit across said check valve and a control for opening said bypass valve only in response to the operation of said valve means placing said upper end of said cylinder portion in flow communication with said source of fluid under pressure through the other of said conduits.
 11. A pressure vessel according to claim 10, wherein said circuit means additionally includes conduits connected into opposite ends of said swing control cylinder portion, valve means for selectively connecting the last said conduits to said source of fluid under pressure whereby to retract and extend said swing control cylinder piston rod to effect horizontal swinging movements of said door, and additional valve means in each of the last said conduits for permitting flow of fluid from an associated end of said lift control cylinder portion only open operation of the last said valve means to connect an opposite end of said swing control cylinder portion to said source of fluid under pressure. 